Dear John,
Take a Person for example, with subclasses Boy and Man. [MW>] The main problem with this is that Boy and Man are not subtypes of person. For Boy and Man to be subtypes of Person, each Boy is a Person, and each Man is a (different) Person. What would be correct is that Boy and Man a subtypes of StateOfPerson, and that each StateOfPerson is a temporalPart of a Person.
To most people, and dictionaries, Boy and Man are subtypes of Person.
[MW>] If that were true it would only mean that most people were wrong.
OED Has:
A male child or youth. Also: a son, irrespective of age (chiefly as referred to by members of the immediate family).
And for child we get:
A young person of either sex, usu. one below the age of puberty; a boy or girl.
In neither case does it say that a child is a subtype of person. If we look at English usage, perhaps we could start with Shakespeare. In as you like it, Act II Scene VII Jacques starts his famous monologue:
“All the world's a stage,
And all the men and women merely players:
They have their exits and their entrances;
And one man in his time plays many parts,
His acts being seven ages. …”
Please note that was seven ages, not seven subtypes.
Second, should a KB contain both a Boy & Man resource about a given individual, owl:sameAs would be used to indicate their equivalence otherwise, yes, they would be a different person, as they should be.
[MW>] Well that is precisely the problem with boy and man being subtypes of person. Now let us suppose that boy A has a start date of 1990-05-03 and end date of 2005-05-03 and the man B has a start date of 2005-05-03, and an end date of 2014-01-15. We now wish to say that boy A and man B are the same person, and decide that OWL:sameas will do. What now is the start date for A=B?
Third, StateofPerson is a wholly artificial term, lacking both practical merit and semantic credibility.
[MW>] State of person is a noun phrase which has quite a precise meaning.
Fourth, this is a fine example of ontologists' implicit saintliness modelling 'concepts' not 'language'.
[MW>] As others have said, I should hope so too. Ontology is about the kinds of things there are and the rules that govern them, not about the language we might use to describe them.
Regards
Matthew West
Information Junction
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